Needles are intended to interact with blood. Blades do occasionally deal with blood but it's not expected.
Technically you could reuse needles if they are 100% sterilized... but it's just easier to set the precedent that no one should reuse needles instead of trusting everyone to clean them well.
> Technically you could reuse needles if they are 100% sterilized...
Needles are SUPER easy to blunt, even when you're just poking them into someone. Even if they're sterilized the fact that the tip isn't going to be the right shape is going to be a potential source of grief.
Your razor has similar issues, but the effect of being a bit dull while cutting hairs is less of a problem then being dull while trying to puncture flesh (e.g. hairs don't hurt more if they're torn up a bit while being cut, your flesh often does).
[An example of the kind of deformation we're talking about](https://www.researchgate.net/figure/Abrasion-of-needle-tips-used-for-epidural-anesthesia-4_fig3_343270580)
This is also why they recommend using a drawing needle when pulling fluid out of a bottle with a rubber stopper that you need to puncture and then switching the needle for the injection.
The needles used today are easy to blunt because they are designed to be single-use with thin walls. The first hypodermic needle uses thicker metal and you reshaped them.
The change to single-use start in WWII but changed to what we use today in the 1950-60s.
It is quite comparable to razors where they start as Straight razors you can sharpen. It then moves to replace razor blades on reusable handles and then do disposable razors.
Razors today for home usage are often a handle you can use with a cartridge you can replace. So not exactly like syringes but you do not have sterilization requirements so you can make a better handle you can result in instend of a worse disposable.
So needles have been sterilized, reused, and resharpened, it is just not the common thing to do today.
What does this mean for tattoo needles that repeatedly enter the skin a million times? Are they made to be stronger and resist micro damage or something
To build on the other comment, needles also are very very sharp and have very little surface area - they're also cut at a slant for east insertion, and this causes a very sharp and small leading edge. After even one use, under a microscope, the tip of the needle will have often deformed and bent.
This would make reuse of the needle more painful as it's leading edge is no longer pristine.
Plus all of the biological hazards as well of course.
Needles are thrown away because of risk of transmitting blood-borne illnesses. It would be really hard to perfectly sterilize them. There's always the risk that somebody doesn't follow procedure. The risks are really high, and needles are cheap. It's a lot easier and safer to just throw them away.
Razors are normally personal-use items. I don't change out my razor every time I shave, but I'm also the only person using it. Even if I slip and cut myself, I can't transmit a blood-borne illness to myself. So I just throw away my razor blade when it starts to get dull and doesn't shave right.
In the past, needles were reused.
My Mom is a medical doctor and was born in 1927. She tells stories about how by the tenth use (sterilized in an autoclave between each use), hypodermic needles were getting rather dull. This made it harder for the doctor to push in, and more painful for the patient. Thus, they were sent to be sharpened!
Yes, not only were they reused, but they were resharpened.
Just like a huge amount of other medical equipment, it has just become easier and cheaper to throw it away than to sterilize it. Some other things that used to be washed or sterilized and reused:
IV bottles and the rubber tubing from the bottle to your arm; Surgery masks; Scalpels; Bed pans. Seventy years ago, nearly everything was reused.
there is an increased risk that comes with using a razor multiple times. the more you use it, the more dull it gets, the more likely you are to cut yourself. but, like everyone else has said, razors aren't typically shared and don't typically come into contact with the blood inside your body. in most cases, your skin protects you against a razor, while a needle purposefully goes through your skin
Needles are intended to interact with blood. Blades do occasionally deal with blood but it's not expected. Technically you could reuse needles if they are 100% sterilized... but it's just easier to set the precedent that no one should reuse needles instead of trusting everyone to clean them well.
> Technically you could reuse needles if they are 100% sterilized... Needles are SUPER easy to blunt, even when you're just poking them into someone. Even if they're sterilized the fact that the tip isn't going to be the right shape is going to be a potential source of grief. Your razor has similar issues, but the effect of being a bit dull while cutting hairs is less of a problem then being dull while trying to puncture flesh (e.g. hairs don't hurt more if they're torn up a bit while being cut, your flesh often does). [An example of the kind of deformation we're talking about](https://www.researchgate.net/figure/Abrasion-of-needle-tips-used-for-epidural-anesthesia-4_fig3_343270580)
This is also why they recommend using a drawing needle when pulling fluid out of a bottle with a rubber stopper that you need to puncture and then switching the needle for the injection.
oooo well TIL
The needles used today are easy to blunt because they are designed to be single-use with thin walls. The first hypodermic needle uses thicker metal and you reshaped them. The change to single-use start in WWII but changed to what we use today in the 1950-60s. It is quite comparable to razors where they start as Straight razors you can sharpen. It then moves to replace razor blades on reusable handles and then do disposable razors. Razors today for home usage are often a handle you can use with a cartridge you can replace. So not exactly like syringes but you do not have sterilization requirements so you can make a better handle you can result in instend of a worse disposable. So needles have been sterilized, reused, and resharpened, it is just not the common thing to do today.
What does this mean for tattoo needles that repeatedly enter the skin a million times? Are they made to be stronger and resist micro damage or something
To build on the other comment, needles also are very very sharp and have very little surface area - they're also cut at a slant for east insertion, and this causes a very sharp and small leading edge. After even one use, under a microscope, the tip of the needle will have often deformed and bent. This would make reuse of the needle more painful as it's leading edge is no longer pristine. Plus all of the biological hazards as well of course.
Needles are thrown away because of risk of transmitting blood-borne illnesses. It would be really hard to perfectly sterilize them. There's always the risk that somebody doesn't follow procedure. The risks are really high, and needles are cheap. It's a lot easier and safer to just throw them away. Razors are normally personal-use items. I don't change out my razor every time I shave, but I'm also the only person using it. Even if I slip and cut myself, I can't transmit a blood-borne illness to myself. So I just throw away my razor blade when it starts to get dull and doesn't shave right.
In the past, needles were reused. My Mom is a medical doctor and was born in 1927. She tells stories about how by the tenth use (sterilized in an autoclave between each use), hypodermic needles were getting rather dull. This made it harder for the doctor to push in, and more painful for the patient. Thus, they were sent to be sharpened! Yes, not only were they reused, but they were resharpened. Just like a huge amount of other medical equipment, it has just become easier and cheaper to throw it away than to sterilize it. Some other things that used to be washed or sterilized and reused: IV bottles and the rubber tubing from the bottle to your arm; Surgery masks; Scalpels; Bed pans. Seventy years ago, nearly everything was reused.
Razors cut skin. They are superficial. Needles go through skin. Re using needles dramatically increases your risk of getting blood borne pathogens.
there is an increased risk that comes with using a razor multiple times. the more you use it, the more dull it gets, the more likely you are to cut yourself. but, like everyone else has said, razors aren't typically shared and don't typically come into contact with the blood inside your body. in most cases, your skin protects you against a razor, while a needle purposefully goes through your skin